Neural Mechanisms as Putative Targets for Warfighter Resilience and Optimal Performance - Neurotechnology in National Security and Defense - page 53

to use tasks of emotion face assessment that we have previously shown to be sensitive
to levels of trait anxiety (Stein et al. 2007), can be modulated by antianxiety drugs
(Paulus et al. 2005), and are well known to be sensitive to genetic differences across
individuals (Hariri et al. 2002). As elaborated below, we hypothesize that limbic and
paralimbic structures play an important role in helping individuals adjust to extreme
conditions. Thus, we hypothesize that the level of resilience critically modulates
activation of the amygdala and insular cortex. In particular, if the anterior insula
plays an important role in helping to predict perturbations in the internal body state,
one would hypothesize that greater activation in this structure is associated with bet-
ter resilience. Moreover, if one assumes that the amygdala is important in assessing
salience in general, and the potential of an aversive impact in particular, one would
hypothesize that greater resilience is associated with relatively less activation in the
amygdala during emotion face processing.
INTEROCEPTION AND ITS NEURAL SUBSTRATES: A NOVEL
APPROACH TO RESILIENCE AND STRESS ASSESSMENT
Interoception comprises receiving, processing, and integrating body-relevant signals
together with external stimuli to affect motivated behavior (Craig 2002, 2009).
Different conceptualizations of interoception have included its definition as the state
of the individual at a particular point in time (Craig 2010), or as the sensing of body-
related information in terms of awareness (Pollatos et al. 2005), sensitivity (Holzl
et al. 1996), or accuracy of the sensing process (Vaitl 1996). Interoception provides
an anatomical framework for identifying pathways focused on modulating the inter-
nal state of the individual. This framework comprises peripheral receptors (Vaitl
1996), c-fiber afferents, spinothalamic projections, specific thalamic nuclei, poste-
rior and anterior insula as the limbic sensory cortex, and anterior cingulate cortex
(ACC) as the limbic motor cortex (Augustine 1996; Craig 2007). Central to the con-
cept of interoception is that body-state relevant signals comprise a rich and highly
organized source of information that affects how an individual engages in moti-
vated behavior. Importantly, interoception is linked to homeostasis (Craig 2003),
which implies that an individual's motivated approach or avoidance behavior toward
stimuli and resources in the outside world is aimed at maintaining an equilibrium.
For example, a person will approach a heat source in a cold environment but avoid it
when the ambient temperature is high.
Interoception is an important process for optimal performance because it links
the perturbation of internal state, as a result of external demands, to goal-directed
action that maintain a homeostatic balance (Paulus et al. 2009). In particular, the
interoceptive system provides information about the internal state to neural systems
that monitor value and salience and are critical for cognitive control processes. We
recently proposed that maintaining an interoceptive balance, by generating body
prediction errors in the presence of significant perturbations, may be a neural marker
of optimal performance (Paulus et al. 2009). This notion is consistent with findings
that elite athletes pay close attention to bodily signals (Philippe and Seiler 2005) and
may be particularly adept in generating anticipatory prediction errors (Aglioti et al.
2008). Moreover, Tucker (2009) has proposed that individuals regulate performance